Call me ignorant, but I played FO3 and NV in a vacuum without knowing who did what. NV's quests came across as so vastly superior to me, and I ended up playing it twice as long as FO3 in spite of greatly preferring FO3's environment. After a while I realized part of it was that the nothing of the Mojave was being utilized so much better than the Capital Wasteland seemed to be. Over time, I've come to think of FO3 as a missed opportunity.
I don't see how anyone missed those subway tunnels though. I could be convinced I was trapped in a Twilight Zone episode down there where every direction you turned looked the same.